lol, hundreds of thousands of people. The amount of space required, rope needed , social skills and management necessary alone is a feet of astonishment moreso than the size of stones and placement.
I can think of an easier way to do it. Level out the land underneath the stones and chisel the stones as they naturally rest. The idea that some stones come from hundreds of miles away is absolute theory and is only based on current geographical locations and there is no hard evidence to support the notion. Doesn't mean granite stones were not already there, why not just remove what is under a pile of stones and chisel out block formations of each stone. Lots of rocky areas where stones just pile on top of each other. Or maybe they used a heard of elephants and whipped them into pulling the stones.
7 degree ramps is another method and doesn't require too many people using logs as rollers. Another would be using Sand to lower the blocks into place as the sand pours out of a built structure.
Anything but aliens, c'mon now.
A demonstration showed using sand and a tall log of sorts with rope spiraled so that each side pulls and it twists the log and the sand carves into the stone. A team of scientists made it work and drilled a hole into granite but doesn't mean that was exactly the original method. I think they used horses to walk around in a circle.